Well the miles have racked up pretty fast on my 2011 Prius, we still have it, almost 151K miles on it. The plugs have never been replaced. We are considering trading when 2016 come out. It still runs good, I can still get well over 50mpg with it. I don't know if the highway miles extend the life of plugs or not. The plugs definitely need changing along with some other stuff if I were going to keep it. What is the most miles anyone has on their plugs in the gen 3 model. It will make me feel better if someone has more that me and make my neglect of not changing them fell better.
Spark plugs are like timing belts, they work fine until they break. Those plugs in your car should be fine as your car's performance is still top notch. It's more of preventive maintenance at 120k
i took it to the 2011 coast and back this past July, got 57mpg round trip of 450 miles. I just took my new 2015 on exact trip and got 58.6 with less than 1 k miles on it. We may just trade the 2011 in on a 2015, some pretty good deals out there. If my math is correct, the $3,000 more dollars I would have to pay for the 2016, I'd never justify a savings in gas in the next 5 years but could be wrong. I've never got this good of gas mileage with the 2011, even when it was new. I'm using better driving habits, a lot of gliding when possible. These tires on the 2015 are Goodyear Assurance fuel max. The tires on the 2011 have always been Energy Saver A/S. I somewhat hyper mile if no one is behind me. I'm usually not in a hurry to get to where I'm going anyway. My air pressure on both cars are 44 front and 42 back. I made an 80 mile trip to a local mountain,today, 80 mile there and back and got 69.4 mpg. The temperature was in the upper 50s most of the ride. No wind to speak of. I ant got nothing else much to do so I ride a lot.
So the plugs, are you going to change them? It's not that hard, mainly frustrating: the crazy amount of disassembly needed. Google "nutzaboutbolts prius spark plug" should find it. You need a 9/16" spark plug socket, maybe a 3" and 6" ratchet extension. Torque with dry thread 15 lb/ft, maybe 13 with a very thin coat of anti-seize. The plug is DENSO SC20HR11. Gap is 1.3 mm (0.0512"). If it's slightly off when you buy them I'd be inclined to leave the as-is: they're fragile and the manufacturer probably got it right.
I had a subscriber on my YouTube channel said that he was a Taxi driver who drove his Prius to 300k+ miles before they replaced the Prius vehicle for a new one. It's not that hard but if you plan on changing vehicles every time there's a new model, that's not a bad idea if you don't want all the hassle of doing the maintenance on them.
Not sure if I will change them or not, depends if we get rid of it or not. Thanks for the information about socket size and extensions needed. I will do it myself I guess if they get done. I saved this information in my files, will be very helpful should I decide to change them. I watched a video once of all the disassemble to get to plugs.
agree on the 2015, great deals! you will never make money on a '16, but you won't make money on the '15 either, you just get a new car.
